Well, Sandy, not only male offspring but 66% male to 33% female. Its called the ladykiller gene (lk) and is carried as a recessive by the male and is sex linked. So the half of his potential daughters who inherit it fail to develop in the egg.

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If you have nothing............ ......... give it away!

Re-read that and realised that its not very clear. Its a recessive, sex linked gene. So one copy can be carried by a cockerel with no detrimental effects to him. However when bred from to any hen then half of his potential daughters die at about the third day of incubation. So,on average, out of twelve fertile eggs you get six cockerels, three pullets and three that die.

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If you have nothing............ ......... give it away!